title: Thermal stability of corn oil flavoured with Thymus capitatus under heating and deep-frying conditions.
abstract: BACKGROUND
  The thermal stability of corn oil flavoured with thyme flowers was determined and compared with that of the original refined corn oil (control). The oxidative stability index (OSI) was measured and samples were exposed to heating (30 min at 150, 180 and 200 °C) and deep-frying (180 °C). Changes in peroxide value (PV), free fatty acid (FFA) content, specific absorptivity values (K(232) and K(270)), colour and chlorophyll, carotenoid and total phenol contents were monitored.
  
  
  RESULTS
  The OSI and heating results showed that thyme incorporation was effective against thermal oxidation based on the increased induction time observed for the flavoured oil (6.48 vs 4.36 h), which was characterised by lower PV, FFA content, K(232) and K(270) than the control oil after heating from 25 to 200 °C, with higher red and yellow colour intensities and chlorophyll, carotenoid and total phenol contents. The deep-frying test showed the accelerated deterioration of both oils in the presence of French fries.
  
  
  CONCLUSIONS
  Compared with the control oil, the thyme-flavoured oil showed improved thermal stability after heating. This could be attributed to the presence of thyme pigments and antioxidant compounds allowing extended oil thermal resistance.
authors.affiliation: Aromatic and Medicinal Plants Unit, Center of Biotechnology of the Technopol Borj-Cedria, BP 901, 2050 Hammam-Lif, Tunisia. iness.karoui@yahoo.fr
authors.forename: Iness Jabri
authors.initials: IJ
authors.lastname: Karoui
authors.forename: Wissal
authors.initials: W
authors.lastname: Dhifi
authors.forename: Meriam Ben
authors.initials: MB
authors.lastname: Jemia
authors.forename: Brahim
authors.initials: B
authors.lastname: Marzouk
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D002338:Carotenoids / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D003116:Color; D003296:Cooking; D003314:Corn Oil / Q000737:chemistry / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000032:analysis*; D005421:Flavoring Agents; D035264:Flowers; D006361:Heating; D006358:Hot Temperature; D015227:Lipid Peroxidation; D010636:Phenols / Q000032:analysis; D046930:Thymus Plant
chemical_list: D000975:Antioxidants; D005230:Fatty Acids, Nonesterified; D005421:Flavoring Agents; D010636:Phenols; D002734:Chlorophyll; D002338:Carotenoids; D003314:Corn Oil